JP-2012-193637A shows a fuel injection system in which a high-pressure pump supplies high-pressure fuel to a common-rail and a fuel injector injects the high-pressure fuel in the common-rail into a combustion chamber of an engine.
A high-pressure pump has a fuel gallery, a pump chamber and a plunger.
When the plunger reciprocates to discharge or suction the fuel, a pressure pulsation is generated in the fuel gallery. The pressure pulsation in the fuel gallery causes insufficient fuel suction. It is likely that sufficient fuel supply is hardly conducted. Moreover, it is likely that oil-tight in a feed passage or a return passage may be deteriorated.
A bladder type accumulator or a pulsation damper can be provided to reduce the pressure pulsation in the fuel gallery. However, in the bladder type accumulator, it is always necessary to keep the gas in a rubber bladder, which takes a time.
Also, in a case that dimethyl ether (DME) is used as principal component of the fuel, it is necessary to use a special rubber material for the rubber bladder. It is likely that a pressure pulsation of high frequency may not be absorbed.
Moreover, in a case that liquefied gas fuel including DME as a principal component is used, the volume of the accumulator and the pulsation damper becomes large in order to absorb the pressure pulsation. However, it is difficult to arrange the accumulator or the pulsation damper having large volume in a fuel supply system for a vehicle.